Robotic Cat in Nasuverse
by rikudo6969
Summary: F/SN, a story about Shirou Emiya, an amateur magus unintentionally involve in a cruel battle called Holy Grail War. But what will happen when a certain robotic cat from 22nd century join the fray?
1. Chapter 1

Today is a beautiful day, more than any other days. Because today is the day the manga Doraemon loves is published. So Doraemon is now waiting for Nobita to come home with the manga.

"Why Nobita-kun is still not home? School is over for a while?" Doraemon muttered as he looked at the clock.

"Doraemon." Nobita called from downstair.

Right, Nobita has been back and in his hand is the manga the two of them want to read. That manga is Fate/Stay Night Full Ver. This thing is thicker then normal because it contains all Fate's events, it includes all 3 routes and the spin-off. And of course it is not cheap. Nobita and Doraemon have to spend all the money they have saved for 3 months.

"Doraemon, I have the manga." Nobita shouted as he entered the room.

"Too late, Nobita-kun. Where has you been?"

"There are many people want this manga too, you know. I have to wait in line."

"Let's read. I can't wait anymore!"

So the two excitedly read it. After a few hours, they have finished.

"This thing is good. Really worth our money right, Doraemon" Nobita said.

"Yeah. But its plot is a little complicated. Do you really understand all of it, Nobita-kun?" Doraemon mockingly asked.

"Hey, don't underestimate me. I can understand it easily." Nobita retorted.

"Yeah right."

Doraemon's sarcastic answer annoys Nobita. When he try to talk back, his mother voice cut in. "Welcome!" Tamako, Nobita's mother said. "Can you come upstair and play with Nobita to let me and your mother talk?"

"Yes."

From the voice, Nobita immediately know who is that."It's that kid. If she crys, no one can sooth her. And mom will scold me." Nobita said worryingly. "I will run first, good luck dealing with her." So saying, Nobita takes the Take-copter and fly out the window, leaving Doraemon alone.

"Oi, don't leave me." Doraemon try to call Nobita but he is already out of sight.

From his voice, Doraemon understands this girl is not easy to deal with. He want to run after Nobita but all of his remain Take-copter is out of battery so he has no way to avoid the disaster coming.

"That's it." Doraemon suddenly shouted. "Picture Book Entry Shoes. With these shoes, I can enter the world Fate/Stay Night to hide from the girl. And maybe I can get the Grail and wish for a world full of dorayaki."

Giggle while thinking that, Doraemon put on shoes and jump to the manga.

 _ ***Scene Break***_

 **At the same time (Emiya's Household)**

Shirou Emiya, son of Kiritsugu Emiya and a amateur magus, is currently fighting with a blue spearmen. If look closely, you can see this is a one-side fight with the spearmen gets the upper hand.

"The trick you use, I can smell magecraft in it. But it's just garbage." Lancer said while pointing his blood-red spear at Shirou. "Can you dodge this?"

Lancer suddenly rush in at full speed and pierce Shirou. Shirou react immediately by reinforce the paper and use it as a shield. But spear completely shatter Shirou shield and make him fly across the yard.

"You have a quick-witted kid" Lancer complimented. "Maybe… You are the seventh. Ma, even if you are, this is the end, kid."

Lancer ready his spear, intent to deal the finishing blow. But suddenly, from the sky, an object fall down and land between the two. After a few moment, the dust clear and reveal a human… no, a strange blue animal.

"It hurts, cough, cough… slow down not in time." The strange animal said.

"What the hell is this? It's a cat, and it can talk, no, this is…" Lancer wondered. "Hey, talking tanuki, where the hell are you from?"

Unbeknowst to Lancer, this was an insult to Doraemon. An intense insult. If there are things that can make Doraemon mad in the world, then the 1st is mouse, and 2nd is this sentence.

"Unforgivable, I'm a cat, not a tanuki. Hey you, I will make you pay for this offending." Doraemon raged.

"Which part of you look like a cat, hah? Your head is round, your hands round, your whole body roung. If you are a cat, then it must be monstrous cat." Lancer sneered.

"Okay, that's it. I'm mad. I won't forgive you even if you apologize. I will blow you to piece."

With that says, Doraemon searched his 4D pocket and… "Memory Bread. Opps, not this. Damn, where is my weapon. Not this, not this either."

Lancer and Shirou stunned. They must be thinking "What the hell is this crazy tanuki doing?"

"Hey tanuki, I don't know what you are, but you have seen me. So you will die too." Lancer shouted as he rushed into Doraemon.

Lancer aimed the spear at Doraemon. He dodged it on time but the shoes was not. His shoes gadget had been cut in half.

"Oh no, how am I supposed to come back now?" Doraemon groaned.

"No need to come back, you will die here."

"Don't think you can kill me easily. Watch this, Legendary Sword _Denkomaru_!"

"You think you can stop me with that toy, don't make me laugh."

Lancer rushed into Doraemon. But not like last time, Doraemon skillfully parried Lancer spear.

 _Clang, Clang, Clang_

The sound of metal meeting metal resounded throughout Emiya Back Yard as two individual clashed against each other with their weapons. Lancer try to stab Doraemon but was deflected. After that, Doraemon made a counterattack swung his sword horizontally causing Lancer to cross his spear to block it. But it was futile as the slash was only a feint.

Doraemon took a large step forward and slashed Lancer across his chest. But with his inhuman reflex of a Servant and speed of Lancer class, Lancer managed to block it but the impact pushed him a few meters back.

"Do you see my power?" Doraemon asked. But in his mind he was surprised that Lancer could block Denkomaru attack.

"Go toe to toe with a Servant. Not bad, tanuki." Lancer amazedly said.

"As I say, I'm not a tanuki. I'm Doraemon."

"Okay, Doraemon. I will begin serious now!"

After the exclaimation, Lancer propelled forward with a speed faster than before. His attack became stronger and more intense which gave Doraemon a hard time to parry.

"Can you block this." Lancer thrusted his spear forward with an impressive strenght. Doraemon tried to block which caused his sword to be blown away. Although Denkomaru could automatically block the attacks, it didn't increase the user's strenght. So a powerful attack can knock the sword away.

Doraemon got into the state of panic, try to run away. He run while searching his pocket "Not this, not that,…"

"Die, tanuki!"

Lancer prepared to pierce his prey heart but unexpectedly, a silhouette rush in and block the spear.

"Your opponent is me." said blond hair girl.

"A Servant? So that guy is the 7th."

Doraemon looked at the girl and looked back to see a bewildered Shirou

"Ah, Shirou has summoned Saber. I'm safe." Doraemon muttered.

"Before we fight, I have a question." Lancer asked. "Your weapon, is it a sword?"

"My weapon?" Saber smiled mockingly before continuing. "Why must it be a sword? It could be an axe, a staff or even… a bow, Lancer." Finished, Saber turned serious, her stance widen, her invisible weapon at her side.

"Interesting, swordsman" Lancer changed his stance. "It's our first meeting, will you agree a draw?"

"I refuse. You will fall here, Lancer" Saber replied calmly.

"Che, if it has come to this. I will have your heart

 **GAE BOLG"**

After the shout, Lancer thrust his spear forward. A red light burst out and go straight to Saber. But a figure stood in front of her, and with just waving the red cloth in his hand, the light has bounced back and stabbed Lancer, leaving a deep wound at his left shoulder.

"What, how…What have you done?" Lancer asked still don't know what happened.

"It's thanks to this, _Reverse Cloak_." Doraemon replied while pointing to the red cloth. "It can reverse an attack to backfire the attacker."

"Gae Bolg, Ireland Child of Light?" Saber asked suprisingly.

"Indentity found, even my Noble Phantasm is countered. It seems today is not my lucky day." Lancer said sarcasticly. "As much as I want to continue this fight, my Master already order me back. He is a coward, you see."

"You want to run, Lancer?"

"You can chase if you want, but at that time, prepare to die." Lancer warned. "And tanuki, the next time we meet it will be your demise."

With that, Lancer run away leaving the three.

"Wait, Lancer." Saber tried to chase but is stop by Doraemon. "Hey, I think you should explain to your Master what happened first."

"Ah, yes, you're right. Thanks for your help from before but, who are you?" Saber asked warringly, still don't know what is this strange creature.

"I'm Doraemon. And I'm not a tanuki, please remember that."

After that, Shirou join in. They do some introduction and some explanation to Shirou. While Shirou still not fully comprehend the situation, Saber suddenly said "I feel a Servant nearby. I will engage now." and jumped out.

"We should follow her." Doraemon suggested. "Okay."

When the two catch up to her, they saw Saber fight with a white-haired man in red and black. Not waste any moment, Shirou demanded "Stop, Saber!"

"What are you doing, Shirou? This is our chance to defeat them. Why stop me?"

"I still don't know what's going on right now. I'm your Master, right? At least let me understand first."

"So to sum up, you are an amateur right?" a female voice could be heard. "Well firstly, good evening, Emiya-kun, and what is that blue tanuki beside you?"

"Tohsaka?"

"Hey, I'm not a tanuki."


	2. Chapter 2

After thinking a couple of reasons to explain everything, Doraemon manages to make everyone accept that he is a robotic cat from the future. But some of them are still not convinced, like Tohsaka Rin for example. To dispel the suspicion, Doraemon decide to use a gadget.

"Y Candle, the one holding this gadget will accept every request that the one giving it says."

"What is this? Why do you gives me?"

"It's nothing important. Just hold it for me."

Rin reluctantly holds the strange object. Suddenly, she feel lighter, like a huge burden has been solved. As a greedy one, this gadget is even more effective with Rin.

"D-Do you really give me such a precious thing? You really are a good person. Doraemon-san is generous, and handsome."

Rin says while crying.

Archer, Shirou, Saber are stunned by her reaction.

"See, do you believe me now? I'm not your enemy and will do anything to stop bad things from happening."

Y Candle's effect wears off. And Rin's face becomes red as tomato from embarrassment because of the "scene" from before.

"Damn you tanuki."

"I'm not a tanukiiii!"

After that, Rin takes Shirou to Kirei to help him understand what he had involved himself in and chooses what he would do from now on. Doraemon doesn't follow them inside the church because he knows who Kirei really is. He don't want to reveal himself to the man yet, especially to a certain King of Heroes. He don't know what they will do if they know about him, but he knows that it will not be a good thing.

Doraemon thinks he will follow Shirou from now on while thinking how to fix the Picture Book Entry Shoes, he is still this manga's protagonist after all. But the most important thing is he don't have money, that means no food.

'I wonder if this world has dorayaki…

Ahhh. I will tell Shirou to make one for me. I know the recipe and he is a good cook.'

Doraemon thinks to himself as he starts grinning happily.

After a few minutes, the group begins going home, with Rin go other way. Suddenly, 2 figure appear before them. One is a silver-haired little girl, and the other is a… monster.

"Berserker…"

Rin says warrily.

"Good evening. I'm Illya, Illyasviel von Einzbern. You know the Einzberns right, Rin?"

The girl greets politely. It's obvious that she is a Master in the Holy Grail War.

"I'm curious. Who is the human-like blue cat beside you, Onii-chan?"

Illya ask while tilting her head cutely. But Rin and Shirou say nothing as all of their attention are on Berserker.

"His parameters are too high. He is superior to Saber in skill.

Archer, attacks him from afar."

"What about your defense? I doubt Rin can take his attack."

"We have Saber here. We will make it somehow."

Rin says in nervous.

"Roger."

With Shirou, despite being an amateur, knows this Berserker guy is a very dangerous monster.

But, Doraemon has an entirely different expression from those two.

"Sob sob, such a moving word."

Doraemon says in tears.

The other look at him confusedly.

"Until now, only Illya-chan calls me a cat. You have become a goddess in my heart."

Illya makes a confused face, still don't understand what that blue cat is saying. But she decides to ignore him.

"… All right, kill them all, Berserker."

Berserker roars loudly and jumps at them, but Archer's arrows push him back. But he stands up unharmed.

Berserker leaps at Shirou, he swings his gigantic sword high, prepares to smash Shirou to pieces. But Saber jumps in to intercept his attack.

Knowing she can't overpower him with strength, Saber decides to lure him into the graveyard, where she has more advantage.

Rin decides to attack Illya, but not forgetting telling Shirou to run away.

"What will you do, Shirou?"

"Of course I will not run away, I will help Tohsaka. Doraemon, thanks for your help from before, but please run. You are not involved in this."

"Shirou, I will come with you."

"Doraemon, you don't need to-"

"Don't worry, despite looking like this, I'm very strong!"

Doraemon excalims proudly, a hand on his chest.

"…Okay. Let's go."

"Ah, wait."

Doraemon searchs his pocket and takes out 2 stickers.

"Here. Please stick it on your body."

"What's this?"

"Just stick it on, I will explain later."

"Okay, okay."

Shirou sticks it on his chest. Then the two run into the forest.

IIIIII

"Shit, this girl is good."

Rin is currently hiding from Illya. It seems she has underestimated her oppoent.

'What should I do-."

A familiar figure snaps her out of her thought.

"That idiot."

Rin says angrily while running to Shirou.

"Ah, Tohsaka-."

Rin skillfully pushes Shirou on the ground without letting him finish.

"You idiot! I already told you to run away. You only hold me back."

"Ma ma, this is what he is. And he still has me."

Doraemon says proudly.

"What can a tanuki like you do? You can't even take care of yourself."

But Rin retorts back.

"Hey, don't be mean. I'm very reliable."

"You're nothing but a tanuki. Which parts are reliable?"

"Youuu…!"

"Enough. What time do you guys think you guys are arguing?"

Shirou steps in.

"He/She starts it."

"Please calm down. We have a bigger problem here."

This seems to calm them down. This is not the time to bicker. The three run out of the forest. In the sight is not a surprising scene, Saber is totally at a disadvantage side. Even changing the place doesn't help much.

Berserker suddenly unleash a powerful strike, blowing Saber away. Taking this chance, Berserker intends to deal the finishing blow, but….

"SABERRR!"

Shirou jumps in, using his body to shield Saber. But before the strike can connect, Berserker is pushed away by an invisible force.

"Phew, I make it it time."

Doraemon says.

"What happened, Berserker?"

Illya confusedly asks. Berserker stands up and tries to attack again. But like the last time, before he can come near Shirou.

 _BANG_

An Invisible force, stronger than before, pushes him back, make him rolls 2, 3 times before stopping.

Both Shirou and Saber, even Tohsaka freeze, don't know what's happening. All eyes now focus on Doraemon.

"Tanuki, what did you do?"

Rin asks the question on everyone head.

"It's thanks to N-S Crest. If two person wear the same Crest, they will repel each other, just like a magnet. I have sticked the same Crest on Shirou and Berserker so if one tries to go near the other, that one will be push away. With this, Berserker can't attack him."

"Ohhh."

Everyone synchronous make an understanding sound.

'So that's why he told me to stick it on before."

'This tanuki, he has many powerful things. Is robot from future this strong?'

Shirou and Rin think.

"It seems I have underestimated you, Cat-niichan. If that is the case, I will eliminate you first. Berserker, kill him."

Hearing the order, Berserker lunges at Doraemon.

"W-What! Don't come here."

Doraemon panickedly run while searching his pocket.

"A a ah, not this, not this, not that…"

Rin, Saber, Shirou look at him with an expression that can't be describe by words alone.

Suddenly, Shirou shouts

"Everyone get down."

A powerful arrow shot from afar, hits Berserker directly.

 _BOOM_

Everyone is blown away by the explosion. Berserker takes a direct hit but

"You have summoned an interesting Archer, Rin.

But Berserker has more than one live."

"What do you mean?"

Rin asks. In the concrete, Doraemon stands up and proudly explain.

"Well, her Servant is Heracles. He has a special NP that gain him 11 extra lives. We need to take him down 12 times if we want to defeat him."

Everyone is stunned at Doraemon's words. Illya is surprised a bit.

"It seems you are more than you look like, Cat-niichan. I have to eliminate you. Berserker, go."

"W-What? This part is where you leave because Archer is interesting, right?"

"I don't know how you get that idea. But please die now."

Berserker lets out a roar and lunges at Doraemon again.

"Oh my god, what should I do? It seems I have to use this. I only use this to give Nobita-kun a lesson before. It's a dangerous gadget, but I have no choice. Watch this.

 **Dictator Switch**."


End file.
